The saga of the mixture screw

[DGXSER]

Ok, I know everyone is probably about done hearing about my stupid mixture screw, but, I will ask for any ideas here.

I had a machine shop drill out the extractor and the screw down to basically the minor dia of the threads (he used blaster and left handed drills in increasing sizes and the thing never budged)a little more is left on one side as in not quite to the threads. So you would think a basic pic of some kind and the left over brass would come out. Of course not! Whatever the PO used to put the gasket on my fork cover with, they used on this mixing screw I guess. It is like it got welded in there. I have a set of picks from Harbour Frieght and the end of the pick is being bent back and forth and the brass is staying put. Soaked in PB Blaster, and put some heat to it. I am still cautious with the heat as the choke seals are right behind it. Not sure how much to apply, but I have seen the blaster smoke.

Headway has been made, but boy is this thing a fighter. Any suggestions would be greatly appreciated.

[tarzan]

Ok,the one I had to fight out did this same thing.I had to bore the hole out in a mill with an endmill.I used a smaller endmill than the minor diameter of the thread.Then I moved the mill over a little to hit the minor,then move the other way to hit on other side.I actually took a little too much on one side but it worked ok anyway.One thing you can do ,is take a 3 sided file(triangle).Grind the end of the file right up to where the cutting serrations start.Then carefully file a light groove in the side of the thread so as to break the thread that is in there.Then try to pick it out.
I would get a dental pick, that is what I used and they are strong. And dig at it where it looks weakest.Can you see aluminum in the threads?If not you might not be close enough.The brass is actually harder than aluminum.
You will probably bugger the threads up a little getting it out but your new screw will probably work ok anyway,at least that was my experience.BTW I broke an end off my pick doing this,but with perserverance and a little patience(not an easy task for me) I got it out.Good luck.

[thewiz]

Don't know if ..

you have a good m/c shop in your area but, if you do, often a good ultrasonic soak will loosen the crud surrounding the stuck screw so it can be more easily removed with conventional methods described on this site.

[Tdog]

Freebie

Happy New year DGXSER,
If, after all of your efforts, you deem the carb unuseable PM me for a carb body. I may have a serviceable spare in need of a new home.
Regards,
Tdog

[DGXSER]

Successs!!!!

WOWW!! I feel like the little engine that could. After the machine shop milled it out close to the threads and right at the minor on one side. I finally decided to pull the choke out, well I got the rubber seal off anyway, and the spring out, and then hit the tunnel with heat much more than I have been.

After the heating, I got a much harder material to use as a pic (a small s/s nail) and used it to get behind the little lip that was above the threads but sealed tight to the wall, once I got that loose and pried on it I got VERY lucky and the rest of the material threads and all, all the way around and down peeled and came out.

Now there is either a little bit of brass left down in the lower threads, or the thing was cross threaded to begin with. I have used one of my old mixture screws to work the threads and only get about half way to three fourths down. So I will be searching for a local shop with a tap for this thread and see if they will let me use it or run it for me. Then I can begin the float setting experience. They already fall within the go-no go gage, I need to do the level check with the tubes on the drains next.

As always, thanks so very much for all the ideas and suggestions and epsecially the offers to let go of the stash of spare parts!!

[tarzan]

One thing that might work to chase that thread is take an old screw and a dremel with a thin wheel,then cut a goove up one side of the thread.The side of the groove that gos in should be fairly square to clear thread.Then use a little light oil and work it in gently.In a couple threads then out,in-n-out-in-n-out.Clean chips out as you go

[DGXSER]

Tarzan,
That is what I eventually did, more or less. I did not cut the groove, but I did use my old mixture screws and plenty of PB blaster for cleaning oil to "tap" the threads. Got it cleaned out pretty good. Got the new screw seating and turns as easily as any of the others.

Now I am going through the bench test, tried skipping it again and this time I got bit. Thought I was fool proof with new float valves and seals, but nooooo, this fool found the way and had fuel pouring out of my air box. Good thing I still have my flushing oil in the engine that is going away anyhow.

Now I am searching and viewing channel 11 instead of making the sandwhich. This might take longer anyway.

[tarzan]

DGXSER,are all your floats level side to side(not crooked).That can make the float height look right if you only measure one side of the float.DAMHIKIJK
And are the floats set at 23mm(.9055 inch)?

[Ivan]

Now I am going through the bench test, tried skipping it again and this time I got bit. Thought I was fool proof with new float valves and seals, but nooooo, this fool found the way and had fuel pouring out of my air box. Good thing I still have my flushing oil in the engine that is going away anyhow.

You got to prime that engine some how don't you?

[DGXSER]

It lives again!!!

Tarzan,
Yes, I checked both sides of the floats and they are as close as the eye can see (my 42 yr old eyes anyway) even.

I pulled the floats on 1 and 2 which both seemed to be leaking and put them back in and never did leak again. 3 and 4 I think the fuel line was kinked and did not flow, nothign came out when I drained them. Bench tested all and no issues. Back on the bike, hooked them up and waited for a few minutes to make sure nothing flowed out then installed the air box connections. Far as I can tell, either there was some minute somehting got under the seats, or the floats got twisted and stuck going form my basement workshop to the garage and on the bike the first time.

After a bit of fussing with the mixtures, it roars to life quite well. Tomorrow suppose to be mid 50's so I may get a ride in to test it all out. Sounds great in the garage though.

[bikerphil]

Nice, glad you got her fired up. In the end, don't forget to sync. Who says these carbs are difficult to work on?

[DGXSER]

Thanks for the reminder on synching Phil. I will repeat it with my one guage method. I tried making the tool and the four way valve I got is crap and does not work, so I just keep moving the tube around from one intake to another. Alot slower I am sure than the other methods, but time is cheaper these days.

All-in-all, the carbs are not that bad. I learned ALOT about methods of getting a stuck screw out, what to do (left handed drill bits, who knew!) and what NOT to do (extractor = LAST resort, and do NOT let it snap off!.) If that mixture screw had not proven to be so difficult, this would have been a one day project. And now I can pull my carbs really quick!